j6 Mr. Cavallo’s Magnetlcal 
trive means of explaining them ; but every confideration feemed 
to confirm the propofition advanced. The principal of thofeob- 
jedions was, that the brafs which becomes magnetic by ham- 
mering and lofes that power by foftening, might contain a 
fmall quantity of iron, to which that magnetic power was 
owing; and that this iron or martial earth, difperfed through 
the fubftance of the brafs, might become phlogifticated by the 
a&ion of hammering ; infomuch as the brafs being forced 
into a fmaller fpace might perhaps give fome of its phlogifton 
to the martial earth, and thus render it magnetic ; and, on the 
contrary, the aftion of the fire in foftening might remove that 
phlogifton from the martial earthy and give it to the brafs ; 
hence the former, remaining quite dephlogifticated, would no 
longer fhew any figns of magnetifm. The confideration that 
iron may be dephlogifticated or calcined more eafily than brafs 
gave an apparent weight to the fuppofition ; but the following 
experiments feem to expel every doubt. 
EXPERIMENT I. 
Having chofen a piece of brafs which would acquire no 
magnetifm by hammering, I placed it upon the anvil, together 
with a confiderable quantity of crocus martis , which crocus had 
no adion on the magnetic needle ; then began hammering the 
brafs, and turning it frequently, in order to let part of the 
crocus adhere to it ; and, in fad, the crocus had in feveral 
places been fattened fo well into the brafs, that hard wiping with 
a woollen cloth would not rub it off. The brafs appeared red in 
thole places ; but, after having been hammered for a long time, 
it acquired no magnetifm whatever. The hardening, there- 
4 fore. 
